Two dimension numerical study of resonant free surface motion in the gap between two fixed vessels

The study focuses on wave induced oscillations of flow inside a narrow gap formed by two identical boxes arranged side-by-side. The problem to be analysed is that of gap resonance behaviours with different gap entrance shapes, incident wave steepness and model scales. We employ the open-source CFD package OpenFOAM and restrict the problem to two-dimensional geometry and fixed boxes. It is found that as wave steepness increases, the frequency corresponding to the maximum response of the fluid in the gap will shift to higher frequency and the response curve closely resembles that of a Duffing oscillator with a hardening spring (as also reported by Vinje, 1991), depending on different entrance shapes. The results also show that a pronounced scaling effect is more evident for cases with rounded corners compared with counterparts with square corners or bilge keels. This may have implications for drawing conclusions applicable to full scale from wave tank tests.